A multifunctional sensing of two carbon dots based on diaminonaphthalenes for detection of ofloxacin drug

Fluorescent carbon quantum dots (CQDs) have gained increased attention due to their diverse properties in the development of sensors and visualizing dynamic processes. This contribution demonstrates the synthesis of two carbon quantum dots, 2,3-CQDs and 1,8-CQDs from 2,3-Diaminonaphthalene and 1,8-Diaminonaphthalene, respectively by hydrothermal process. The results showed that the two CQDs had distinct optical properties with different sizes and therefore we observed different sensing performance and different dynamics interactions, which is dependent on the geometrical structure of precursors. Both CQDs exhibit bi-exponential decay curves with long and short-lived decay components, corresponding to recombination from the defect and intrinsic states, respectively. The sensing performance of 2,3-CQDs which possess high fluorescence quantum yield (0.2) demonstrates an ability to detect Ofloxacin based on fluorescence-enhanced turn off- on with a low detection limit of 0.46 μM and good linear range of 0–120 μM. Meanwhile the sensing of 1,8-CQDs with a quantum yield of 0.17 was performed for detection of Ofloxacin based on fluorescent turn-on–off due to energy transfer mechanism with wide linear response range of 0–120 μM and a satisfactory detection limit of 24 nM. These results indicate that we can adapt our systems to the intended applications by specifically and selectively altering carbon dots.